1. Field of the Invention
The present invention relates to an apparatus for driving a plurality of display units in a mobile electronic apparatus.
2. Description of the Related Art
Recently, in a mobile electronic apparatus such as a mobile telephone apparatus, a plurality of display units, i.e., a main display unit and a sub display unit are provided on an inner side and an outer side, respectively, of a lid pivotally coupled to a body. This will be explained later in detail.
In a stand-by mode, the lid is closed to prepare for an incoming call. In this case, an antenna mark, a clock, a battery residual mark and the like are displayed on the sub display unit. On the other hand, in an operation mode, the lid is opened while the main display unit is being operated.
Also, if a camera function is incorporated into the mobile telephone apparatus, one of the main display unit and the sub display unit is used as a finder, which also will be explained later in detail.
A first prior art driving apparatus for driving the main display unit and the sub display unit is constructed by driver circuits for driving the main display unit and driver circuits for driving the sub display unit. This also will be explained later in detail.
In the above-described first prior art driving apparatus, however, since the driver circuits are provided individually for the main display unit and the sub display unit, the driving apparatus is increased in size and in cost.
In a second prior art driving apparatus for driving the main display unit and the sub display unit, the scan lines (row side lines) of the sub display unit are short-circuited to the corresponding lines of the main display unit, or the data lines (column side lines) of the sub display unit are short-circuited to the corresponding lines of the main display unit, so that the number of driver circuits is decreased. This also will be explained later in detail.
In the above-described second prior art driving apparatus, however, since the parasitic capacitance of the scan lines (row side lines) or the parasitic capacitance of the data lines (column side lines) is substantially increased, the power consumption is increased. Also, in order to drive the increased parasitic capacitance, large-sized drive transistors would be required, which increases the apparatus in size and in cost.